Rotate shift code division multiplex communication system

Abstract

A system using a transmitter which comprises means of generating 4 extended sequences E A0 , E A1 , E B0 and E B1 using a set (A 0 ,A 1 ) of auto-complementary sequences with length L chips consisting of complete complementary sequences and another similar set (B 0 ,B 1 ), and means of generating a transmitting frame s P obtained by multiplying a cascaded sequence Ê A made of extended sequences E A0 and E A1 by a pilot information {circumflex over (p)}, generating a transmitting frame s D obtained by multiplying a cascaded sequence Ê B made of extended sequences E B0 and E B1 by data b, synchronously adding both the transmitting frames to produce a symbol frame, and transmitting a carrier wave modulated thereby, and a receiver which comprises means of applying a front portion r 0 of the synchronously received baseband frame demodulated by above described carrier wave to matched filters M(A 0 ) and M(B 0 ), and applying a rear portion r 1 of the synchronously received frame to matched filters M(A 1 ) and M(B 1 ), and means of generating a pilot-response-matrix {p} and a received data-response-matrix Φ, both made of the outputs of M(A 0 ) and M(A 1 ), and of the outputs of M(B 0 ) and M(B 1 ) respectively, and generating an estimate {tilde over (b)} of transmitted data.

1 . A cyclically shifted code division multiple access communications system is characterized, in a direct-sequence spread-spectrum CDMA communications system that each transmitter comprises a function of generating extended sequences which are composed by arranging a rear and a front portions of a core-spreading-sequence or zero sequences respectively at the front and the rear outsides of the core-spreading-sequence as guard-sequences, 
 a function of modulating the extended sequences with transmitting information to produce a transmitting data-frame,    a function of modulating the extended sequences with pilot information to produce an isolated pilot-frame that is not affected by data-frames and pilot-frames transmitted by the other transmitters, and    a function of transmitting data and isolated pilot-frames; and    a receiver comprises a function of receiving a synchronously received data-flock-frame on a position synchronized with the core-sequence in the extended sequence coming from the desired station,    a function of receiving a similar synchronously received isolated pilot-flock-frames,    a function of analyzing both the flock-frames, generating the received data-response and pilot-response,    the transmitter comprises means of generating the 4 extended sequences E A0 , E A1 , E B0  and E B1  using a set (A 0 ,A 1 ) of the auto-complementary sequences with sequence length L chips composed the complete complementary sequences having the complete complementary characteristics each other and another similar set (B 0 ,B 1 ),    means of generating a transmitting pilot frame s p  made by multiplying a cascaded sequence Ê A  composed of the extended sequences E A0  and E A1  by a pilot information {circumflex over (p)}, generating a transmitting frame S D  made by multiplying a cascaded sequence Ê B  composed of the extended sequences E B0  and E B1  by a data b, synchronously adding both the multiplied outputs to produce a symbol frame, and transmitting a carrier wave modulated by said frame, and    the receiver comprises means of applying a front portion r 0  of the synchronously received baseband frame demodulated by above-described carrier wave to a filter M(A 0 ) that matchs to A 0 , applying a rear portion r 1  of the synchronously received frame to a filter M(A 1 ) that matches to A 1 , and generating a pilot-response matrix {p} corresponding to pilot information {circumflex over (p)} by adding both the matched filter outputs synchronously,    means of applying front portion r 0  and rear portion r 1  of the synchronously received frame to similar matched filters M(B 0 ) and M(B 1 ) respectively, and generating the received data-response-matrix Φ corresponding to the data b by adding those outputs synchronously,    means of generating an estimate {tilde over (b)} of the transmitted data from which the influence of the preceding or delayed waves due to multipath is removed, using pilot response {p} and received data response matrix Φ, and means of detecting the transmitted data {circumflex over (b)} by making estimate {tilde over (b)} x  on the hard-decision.    
     
     
         2 . A cyclically shifted code division multiple access communications system according to  claim 1  is characterized in that the transmitter comprises means of generating cascaded sequence Ê B (n) made of extended sequences E B0 (n) and E B1 (n) which are obtained by cyclically shifting extended sequences E B0  and E B1  by n(=0, 1, 2, . . . L−1) chips, producing a transmitting frame s n  by multiplying cascaded sequence Ê B (n) by data b n , producing a transmitting symbol frame by adding L pieces of s n  and pilot frame s p  according to  claim 1  synchronously, and transmitting a carrier wave modulated by said transmitted symbol frame, and 
 the receiver comprises means of applying front portion r 0  and rear portion r 1  of the synchronously received frame to matched filters M[B 0 (n)] and M[B 1 (n)] that matches to sequence B 0 (n) which is obtained by cyclically shifting core sequence B 0  by n chips and similar sequence B 1 (n) respectively, producing received response matrix Φ by synchronously adding said matched filter outputs, solving a system of linear equations composed of Φ, pilot matrix P generated by above-described {p} and an unknown matrix {tilde over (b)}(n), and detecting L data by making solved data estimates {tilde over (b)}(n) on the hard-decision.  
 
     
     
         3 . A cyclically shifted code division multiple access communications system according to  claim 1  is characterized in that the transmitter comprises means of producing the extended sequence E A0K  with period T E  by arranging guard sequences at the front and the rear outside of a repeated core-sequence with time width T G  which is made by repeating core-sequence A 0  by K times, generating extended sequences E A0K , E A1K , E B0K  and E B1K  using complementary sequences, 
 means of generating a cascaded sequence Ê AK  made of extended sequences E A0K  and E A1K , and a cascaded sequence Ê BK  made of extended sequences E B0K  and E B1K , generating modulated frames Ê AK /f k  and Ê BK /f k  obtained by modulating orthogonal carrier waves f k (k=0, 1, 2, . . . K−1) whose frequencies are different one another by integer times of the reciprocal of core frame period T G  by cascaded sequences Ê AK  and Ê BK , generating a transmitting frame s pk  by modulating Ê AK /f k  by pilot information {circumflex over (P)} k  and a transmitting frame s Dk  by modulating Ê BK /f k  by data b k , and transmitting said transmitting frames synchronously, and  
 the receiver comprises means of applying front portion r 0  and rear portion r 1  of the synchronously received frame to matched filters M(KA 0 /f k ), M(KB 0 /f k ), M(KA 1 /f k ) and M(KB 1 /f k ) that match to the above-described repeated core sequences on carrier wave f k  respectively, generating pilot matrix {p} k  of the k-th user u k  and data response matrix Φ k  of u k  by adding synchronously the former two matched filter outputs and the latter two matched filter outputs, respectively, and obtaining estimate {tilde over (b)} k  of transmitted data b k  by solving a system of linear equations composed of these matrices.  
 
     
     
         4 . A cyclically shifted code division multiple access communications system according to  claim 3  is characterized in that the transmitter generates cascaded sequence Ê B (n) made of extended sequences E B0 (n) and E B1 (n) which are obtained by cyclically shifting the extended sequences E B0  and E B1  by n(=0, 1, 2, . . L−1) chips, and composing a transmitting frame obtained by modulating cascaded sequence Ê BK (n) on orthogonal carrier wave f k  by transmitting data b kn (0, 1, 2, . . . L−1) of user u k , and 
 the receiver applies front portion r 0  and rear portion r 1  of the synchronously received frame to matched filters M[B 0 (n)] and M[B 1 (n)] that match to sequence B 0 (n) which is obtained cyclically shifting by n chips of core sequence B 0  and to similar sequence B 1 (n) respectively, producing received response matrix Φ which is obtained by synchronously adding said matched filter outputs, solving a system of linear equations composed of Φ, pilot matrix P generated by above-described {p} and an unknown matrix {tilde over (b)}(n), and demodulating data b kn  which user u k  has transmitted, in a process of detecting L data by making solved data estimate {tilde over (b)}(n) on the hard decision.  
 
     
     
         5 . A cyclically shifted code division multiple access communications system according to claim ( 3 ) or ( 4 ) is characterized in that Q(=2, 3, . . . ) pieces of orthogonal carrier waves is assigned to the data transmission for user u k , and the receiver demodulates using a common pilot information thereby the transmission capacity of each user is increased.  
     
     
         6 . A cyclically shifted code division multiple access communications system according to  claim 1  is characterized in that the pilot information is transmitted once in multiple N frames, and the data information is transmitted using the other (N−1) frames.  
     
     
         7 . A cyclically shifted code division multiple access communications system according to  claim 5  is characterized in that the pilot information is transmitted once in multiple N frames, and the data information is transmitted using the other (N−1) frames.